An image signal processing apparatus and image signal processing method obtains a high super-resolution effect for distorted images captured by a specialized optical system, such as a 360-degree camera. A distortion-correction conversion-formula calculation section calculates a distortion correction conversion formula for correcting the nonlinear distortion. A distortion correction and interpolation processing section performs distortion correction and interpolation processing on each cropped region. An alignment conversion formula calculation section calculates an alignment conversion formula for alignment between each cropped image after distortion correction and interpolation processing is completed. A pixel coordinate conversion section rearranges pixel coordinates for each frame image before interpolation processing by using the distortion correction conversion formula and the alignment conversion formula corresponding to the cropped regions. An image synthesis section synthesizes the cropped images.